Polyethylene terephthalate has been recently used as a support for a magnetic recording medium. Polyethylene terephthalate has excellent mechanical strength and durability with respect to exposure to organic solvents. These properties are present because the polyethylene terephthalate is stretched and highly crystallized. Magnetic recording media are produced by coating a coating composition comprising a ferromagnetic fine powder dispersed in a binder on a support. Many attempts have been made to firmly adhere the magnetic recording layer (coating composition) to the support.
For example, methods for providing a subbing layer between a magnetic layer and a support are disclosed in U.S. Pat. No. 3,730,767, Japanese Patent Publication No. 10243/74, Japanese Patent Application (OPI) Nos. 46406/74, 46407/74, 32905/75, 32906/75 and 32907/75. These are not satisfactory due to the composition of the subbing layer.